I love question posted in the forum, group site and blog. In the end it gives me an idea to do quick tutorial. The subject :how to Model a curtain in SketchUp" is a question at Sketchunesia. Let me answer it using this tutorial with bonus on how to even apply a believable material.

However, is not just the translucency. Sheer curtain sometimes has transparency and reflective properties; therefore it is important to consider the material that you will put in front and back of the two sided material. Here is my setting.

Diffuse is a Blend map; a combination of a bitmap and Acolor which the main color of the map[You must be registered and logged in to see this image.]

Diffuse color has slight transparency. For me this very important to enhance translucency.[You must be registered and logged in to see this image.]

My refraction layer.. Using fresnel map.[You must be registered and logged in to see this image.]

My reflection map. Using like a mirror but black color. [You must be registered and logged in to see this image.]